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Do What You Can to Ease Side Effects of Treatment and Symptoms of Colorectal Cancer

Each treatment option has its own set of side effects. You should talk with your doctor about what to expect with your treatment. You can also ask for your doctor’s help in dealing with side effects. In this section we discuss the most common side effects that people have while they are being treated for colorectal cancer. You will not likely have all of these side effects or symptoms. They are listed alphabetically to help you find information when you need it. These side effects are usually temporary and do not normally cause serious problems if they are addressed. 

It’s also important to remember that your cancer can have both a physical and a mental effect on you. Talk with your doctor about how your cancer is making you feel. There are things you and your health care team can do together to deal with issues such as pain, anxiety, and depression.

Anxiety and depression

Many people feel blue, anxious, or distressed after being told they have cancer. These feelings may continue or come back throughout treatment.

Taking these actions may ease your mental stress:

  • Talk to your family or friends.

  • Consider joining a cancer support group or finding a cancer “buddy” who can help you cope.

  • Ask your doctor about medications for depression and anxiety.

  • Ask your doctor for a referral to a social worker, psychologist, or psychiatrist.

Appetite loss

People who eat well during cancer treatment maintain their strength better and tend to be more active. When you're being treated for cancer, a diet high in calories and protein is best. The problem is that side effects of treatment can change or reduce your appetite. Chemotherapy can make you nauseated, change the way food tastes, or make you too tired to want to eat. Radiation can also cause nausea, which can reduce your appetite.

Ask your doctor for a referral to a registered dietitian if you are having trouble maintaining your desire to eat. Also, try these tips to stimulate your desire to eat:

  • If you can, eat foods high in protein several times a day. These foods include milk, cheese, cottage cheese, yogurt, meat, fish, eggs, beans, peanut butter, and nuts. Protein helps build and repair tissue, and cancer treatments cause you to use more protein than usual.

  • Ask your doctor, nurse, or dietitian about high-protein drinks that can help supplement your diet.

  • If you can, eat high-calorie foods to help you maintain your weight, such as margarine or butter, sugar, honey, jams, jellies, cream cheese, dried fruit, gravies or sauces, mayonnaise, and salad dressing.

  • Get plenty of fluids to help control your body temperature and improve bowel function. In addition to water, fruit juices, and other liquids, try these foods to increase fluids: gelatin, pudding, soups, Popsicles, and ice cream.

  • Eat small meals throughout the day instead of three large ones.

  • Keep snacks handy to eat when you are hungry.

  • Eat with friends or play your favorite music at mealtime to boost your appetite.

  • Eat your biggest meal in the morning. Many people getting treatment for cancer find that this is when their appetite is greatest.

  • If you can, increase your activity level. Doing so may stimulate your appetite.

  • On days you don't feel like eating at all, don't worry about it. Try again the next day. If you find your appetite doesn't improve in several days, talk with your doctor or nurse. 

Bladder damage

Bladder damage is possible with radiation therapy. This could lead to bladder spasms and frequent, urgent, or burning urination. Your doctor can prescribe medication to help prevent spasms. Drinking more liquids during your treatment period will also help prevent these kinds of problems.

Bleeding or bruising

Throughout your treatment, your doctor will take small samples of your blood for testing. One thing he or she is checking is your number of platelets. Without enough platelets, your blood may have difficulty clotting. You may bleed or bruise easily. Although it is rare that a platelet count drops low enough to be dangerous, you should be aware of bleeding gums or nosebleeds and report them to your doctor. They could be signs that your platelet count is too low. If your doctor tells you that your platelet count is low, take these actions to avoid causing injuries that could lead to uncontrolled bleeding:

  • Protect your skin from cuts, scrapes, and sharp objects.

  • Shave with an electric razor. Take care when using fingernail or toenail cutters. 

  • Use a soft toothbrush to prevent bleeding gums. Be gentle if using dental floss or toothpicks. Check with your doctor before you have any dental work done. 

  • Take steps to prevent constipation, which can lead to rectal bleeding or hemorrhoids.

  • Avoid contact sports or situations where you might be injured. 

  • Call your doctor if you develop a rash, bleeding, or bruising. This includes black, tarry stools; blood in urine or stools; or red pinpoint spots on your skin. 

  • Check with your doctor before taking aspirin, ibuprofen, or other pain relievers; vitamin E; or any other drugs or dietary supplements. Some of these may increase your risk for bleeding.  


Either radiation or chemotherapy can cause diarrhea. When you are having both treatments at once, the problem can be especially severe. The biggest danger when you have diarrhea is dehydration. It’s important to drink plenty of water and other liquids to replace the fluids your body loses. You can also use these tips to help control your diarrhea:

  • Ask your doctor about medications that may help and take any medications as prescribed. Don’t take over-the-counter medicines without first asking your doctor.

  • Avoid milk and milk products.

  • Eat smaller meals more frequently.

  • Choose foods that are low in fiber. This kind of diet is often called a low-residue diet. Foods such as bananas, rice, applesauce, and toast are good choices.

  • Increase your intake of fluids, such as broth. If the diarrhea is severe, your doctor may suggest an all-liquid diet for a few days to give your bowels a rest.


Fatigue is a very common symptom and a common side effect from chemotherapy and radiation treatments. You may feel only slightly tired, or you may suffer from extreme fatigue. Taking these actions may help increase your energy level. Fatigue can last several weeks after treatment ends:

  • Take short rests when you feel tired. Avoid long naps during the day so that you can sleep well at night.

  • Add mild exercise, such as walking, to your daily routine. Exercise changes your metabolism and makes it easier for you to rest.

  • Save your energy for important tasks.

  • Drink plenty of fluids.

  • Take action to treat a poor appetite because eating improperly can make you tired.

  • If your fatigue is severe or chronic, ask for help with routine tasks that can drain your energy, such as grocery shopping or housework. Some people reduce their hours at work.

Hair loss (alopecia) 

Losing your hair can be upsetting because baldness is a visible reminder that you are being treated for cancer. Keep in mind that your hair will probably grow back after treatment. Try these coping tips:

  • Consider cutting your hair before treatment starts.

  • Think about getting a wig, hat, or scarf before your hair loss starts. That way, you can get a wig that matches your hair.

  • Because your scalp may be more sensitive to temperature and sun, protect it with sunscreen and hats or scarves. 

Increased infections

Throughout your treatment, your doctor will take small samples of your blood for testing. One thing he or she is checking is your number of white blood cells. Both radiation and chemotherapy can cause a reduction in your white-blood-cell count. Without enough white blood cells, your body may find it hard to fight infection. If your doctor tells you that your white-blood-cell count is low, you’ll need to be extra cautious about staying healthy:

  • Avoid crowds or people with colds or infections.

  • Avoid young children who have had recent vaccinations with live viruses.

  • Wash your hands often throughout the day to kill germs.

  • Be extra careful to avoid cuts and open sores that could become infected.

  • Call your doctor right away if you have any of these signs of infection: a temperature of 100.5° or higher; severe chills, a cough, pain, or a burning sensation during urination; or any sores or redness.

Mouth sores called stomatitis

Sores in and around the mouth are a common side effect with certain drugs that are used in chemotherapy, such as 5-FU. The best way to address this problem is by practicing good oral hygiene and choosing foods that do not irritate the sores. These steps can help prevent sores or lessen your discomfort:

  • See your dentist to have your teeth cleaned before treatment starts.

  • Brush your teeth often with a soft toothbrush.

  • Keep your mouth and lips clean and moist. Suck on sugar-free candies or fruit bars or chew sugar-free gum to increase moisture in your mouth and to help with changes in taste. 

  • If you have dentures, make sure they fit well.

  • Eat soft foods, such as applesauce, cottage cheese, and scrambled eggs.

  • Avoid spicy, salty, or coarse foods and foods with acid such as tomatoes or orange juice.

  • Avoid alcohol and mouthwashes containing alcohol because they can irritate the sores.

  • Avoid tobacco.

  • Ask your doctor about medications you can put right on the sores to relieve the pain.

Nausea or vomiting

Nausea or vomiting from chemotherapy or radiation treatment may range from barely noticeable to severe. It may help you to understand the different types of nausea:

  • Acute-onset nausea and vomiting occurs within a few minutes to several hours after chemotherapy. The worst episodes tend to be 5 to 6 hours after treatment, and the symptoms end within the first 24 hours.

  • Delayed-onset vomiting develops more than 24 hours after treatment.

  • Anticipatory nausea and vomiting are learned from previous experiences with vomiting. As you prepare for the next dose of chemotherapy, you may anticipate that nausea and vomiting will occur as it did previously, which triggers the actual reflex.

  • Breakthrough vomiting occurs despite treatment to prevent it. It requires additional treatment.

  • Refractory vomiting occurs if you’re no longer responding to antinausea treatments.

To prevent nausea, take these actions. Most nausea can be prevented:

  • Ask your doctor about getting a prescription medicine to control nausea and vomiting. Then make sure you take it as directed. If you are vomiting and cannot take the medicine, call your doctor or nurse.

  • If you have bothersome nausea and vomiting even though you are taking your medicine, call your doctor or nurse. Your medicine can be changed.

To help ease nausea or vomiting, try these tips:

  • Try eating foods and drinking beverages that were easy to take or made you feel better when you’ve had the flu or were nauseated from stress. These may be bland foods, sour candy, pickles, dry crackers, ginger ale, flat soda, or others.

  • Do not eat fatty or fried foods, very spicy foods, or very sweet foods.

  • Eat room-temperature or cold foods. The smells from hot foods may make your nausea worse.

  • Ask your doctor or nurse if he or she can help you learn a relaxation exercise. This may make you feel less anxious and more in control, and decrease your nausea.

  • Ask your doctor or nurse about using acupressure bands on your wrists, which may help decrease your nausea.

Numbness, tingling, or muscle weakness in your hands or feet (from peripheral neuropathy) 

If you have numbness, tingling, or weakness in your hands and feet, you may have nerve damage. This is called peripheral neuropathy. Some types of chemotherapy can cause this. Other signs of this problem are ringing in your ears or feeling too hot or too cold. If you have symptoms such as these, take precautions to protect yourself: 

  • Take extra care walking and moving so that you don't fall. Consider using a shower chair or railing to decrease your risk of falling while bathing.

  • Take care of your feet, and look at them often for signs of injuries or sores. Wear shoes when walking, even when at home. 

  • To prevent burns, use warm, not hot, water for bathing and washing since you may not be able to sense temperature as well in damaged areas. Use a thermometer to check the temperature of the water. It may help to turn down the temperature of your hot water heater to help lower the risk of scalding. 

  • If your daily activities become hard, ask your doctor for a referral to an occupational therapist or a physical therapist. They can help teach you new ways of doing things so that you can stay as active as possible.

  • Take extra care when driving since you may have trouble feeling the gas and brake pedals. Ask friends and family to drive you places. 


If you have surgery, you will have pain from the incision. You may get pain medication in one of these ways:

  • Intravenously, given continuously through your vein. You may have control over how often to get this in a form called patient-controlled analgesia (PCA).

  • Intramuscularly, injected periodically into your muscle

  • In pill form, taken periodically

Don’t be afraid to take pain medication. You won’t overdose, if you are using a PCA, because the doses are set. And because of the way the machine is set up, you will not become addicted. It is important that you get up out of bed and move around as quickly as possible so that you lower your risk for pneumonia and clots in your legs and to help your bowel function return. And you will likely need pain medication to do this.

You can also try these tips to ease pain:

  • Take your pain medications regularly; don’t wait for your pain to become severe. Ask your doctor how you can avoid constipation, a common side effect of pain medications.

  • Change your activity level. See if you feel better if you rest more or move around more--either may help.

  • Distract yourself with music, funny videos, or computer games. (Laughter can really make a difference.)

  • Use heat, cold, relaxation techniques (such as yoga or meditation), or guided imagery exercises. Ask your doctor or nurse where you can learn more about these techniques. Keep in mind that these complement, but do not replace, standard medical practices.

Sexuality changes

Colorectal cancer treatments can cause some long-term side effects related to sexuality. These can be serious, so you should discuss them with your doctor before treatment begins. For some problems, such as reduced sperm count, there are things you can do first to reduce the impact the side effect has on your life:

  • Early menopause. If you’re a woman who has not gone through menopause, you may experience menopausal symptoms. Your period may stop, and you may become infertile. Talk with your doctor about the possibility of taking hormone replacement drugs to relieve these symptoms. If you’re planning on having children, you may want to discuss options with your doctors prior to the start of therapy.

  • Vaginal dryness. Women may experience vaginal dryness and vaginal narrowing. Both conditions are permanent, but they can be treated with lubricants and by using a vaginal dilator or having sexual intercourse.

  • Decreased sperm count. Men may produce less ejaculate, and their semen may have a lower sperm count. If you’re planning on having children, you may want to save your sperm in a sperm bank before having your radiation treatments.

  • Sexual dysfunction. You may have a reduced interest in and ability to have sex, especially if you have surgery for rectal cancer. Talk with your partner about changes in your desire or ability to have sex. Explore new ways to share affection and intimacy. See a counselor who specializes in sexual problems.

Skin irritation

Radiation treatment can cause dry or red skin in the area being treated:

  • Ask your doctor or nurse what kind of lotion you can use to moisturize and soothe your skin. Don’t use any lotion, soap, deodorant, sunblock, perfume, cosmetics, or powder on your skin within two hours before and after treatment.

  • Wear loose, soft clothing over the treated area.

  • Don’t scratch, rub, or scrub treated skin.

  • Don’t bandage skin with tape. If you must bandage it, use paper tape and ask your nurse to help you place the dressings so that you can avoid irritation.

  • Don’t apply heat or cold to the treated area. Bathe only with lukewarm water.

  • Avoid prolonged exposure to the sun.


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